Homebrew PCBs

>> andrewm wrote:
>> I agree that 8/8 is quite do-able with a
>> contact frame and UV tubes.

> DerekH wrote:
> 6/6 is doable here but I've never had
> reason to with anything real. Here is
> tortuous 6/6 artwork, this photo doesn't
> do it justice due to moire and other
> artifacts;
> 
> http://www.pbase.com/eldata/image/62158168
> 
> Here's a closeup of a section;
> 
> http://www.pbase.com/eldata/image/62158260
> 
> Basically, it's 150 concentric rectangles
> resulting in 300 parallel horizontal and
> vertical 6 mil tracks with 6 mil spacing.
> I can do a faithful reproduction in copper
> without collimation which leads me to 
> believe the need for collimation at these
> pedestrian resolutions is a myth.

Derek - what are you using as a phototool
to get good 6/6 ?

I can get 6/6 when I borrow a fancy laser
printer to print on vellum.  However my
personal laser printer at home (HP Laserjet
4xxx) does not give me enough contrast to
get realy reliable mask down there.

In fact the difference between the car
priced 1200 dpi colour laser I borrow and
my 1200dpi monochrome HP is quite amazing.
With my HP I can do 8/8 tracks and have
them look pretty good but large copper
areas get pinholes and washouts in them.

With the borrowed printer large areas of
black stay perfectly black and you can see
2 pixel wide (600dpi) jaggies on diaganol
lines after etching.  8/8 looks perfect
and you can't see any rough edges to the
lines at all with a desk magnifier.